Patent GB-666921-A (GB)
Title: Improvements in and relating to helicopters
IPC: B64C27/04
Filed: 1949-07-15
Abstract: 666,921. Multi-rotor helicopters. CIERVA AUTOGIRO CO., Ltd., PULLIN, C. G., and SHAPIRO, J. S. Oct. 16. 1950 [July 15, 1949]. No. 18685/49. Class 4. A helicopter incorporates a propulsive airscrew or airscrews and a fixed wing capable of a substantial contribution to the total lift in forward flight, and has two or more lifting rotors of which at least one is disposed forward and at least one aft of the centre of gravity, the rotors and propeller(s) being driven by the same engine(s), and also incorporates control means providing for, (a) pitching control of the aircraft by fore and aft differential collective pitch control coupled with, (h) common cyclic pitch control for adjustment of the disc-incidences of all the rotors in the sense to decrease incidence when the pitching control is operated to impose or increase a nose-down pitching moment and conversely, and (c) common collective pitch control, a controllable propeller clutch or clutches and means for varying the datum-settings of controls (a), (b) and (c) so interconnected with the propeller clutch(es) that, when the clutch(es) engage(s), control (a) is adjusted to trim the aircraft in the tail-down sense, control (b) is adjusted to impart a positive movement to the disc-incidences, and control (c) is adjusted to decrease the collective pitch of the rotors. General arrangement, Fig. 3.-The aircraft illustrated comprises three lifting rotors 10, 11, 12 arranged in arrow formation, the rotor 10 being located on the longitudinal axis forward of the centre of gravity while the rotors 11, 12 are placed side by side aft of the centre of gravity and are mounted at the tips of wings 14, 15 of tapered plan form at the rear of the fuselage 13. Engines 22, 23, which are preferably of the gas-turbine type, are carried at the ends of stub-wings 24, 25 and drive propellers 26, 27 and also the lifting rotors through shafts and gearing 28, 29-35. Twin fins 16, 17 form the fairings for the rear undercarriage legs, and trailing edge flaps may be mounted on the wings 14. 15, 24 and 25. Rotor controls, Fig. 6.-Collective pitch of the individual rotors is controlled by rods 99, 100, 101 at the ends of a three-armed spider 112 universally mounted on the upper end of a vertically movable pillar 114, while cyclic pitch control is effected by rods 105, 106, 107 at the ends of a T-bar 133, connected by a transverse pivot to the upper end of a second vertically movable pillar 135. Controls (a) and (b) referred to above are effected bv fore and aft movements of a control column 76 connected to the spider 112 by members 79, 125, 124, 117, 123, and also connected to the T-bar pillar 135 by members 79, 145, 143, 142, 141. Movement of the rod 123 causes tilting of the spider 112 about a transverse axis to apply fore and aft differential collective pitch control to the rotors, while movement of the pillar 135 results in equal movements of the rods 105, 106, 107 to apply common cyclic pitch control to the rotors. Control (c) is effected by a collective pitch control lever 84 operating through members 85, 86, 130, 129, 128 to cause vertical movement of pillar 114. Rolling control is exercised by transverse movement of the column 76 to tilt the spider 112 about a fore and aft axis through members 77, 78, 122, 121, 120, 116, 118, 119. In addition, control in yaw is obtained by movement of a rudder bar 81 which, through members 82, 83, 111 and cable 108 applies cyclic pitch control to the front rotor 10 only, to incline its lift vector transversely. Propeller controls, Fig. 5.-The propeller 27 is freely mounted on a hollow shaft 40 splined to the engine drive shaft 39, and can be coupled to the shaft 40 by engaging a sleeve 57, which is splined to the propeller hub, with a clutch 61 splined to the shaft 40. The sleeve is operated by a lever 64 and rod 66. The propeller may be braked by engaging the sleeve 57 with a fixed member 44. A second sleeve 69 operated by a lever 70 and rod 72 varies the pitch of the propeller blades. The rotor drive shaft 29 is coupled to the engine shaft 39 by a sliding clutch 51, operated by members 54, 56, a oneway clutch 47, and bevel gearing 45, 46. Combined rotor and propeller controls.-The conjoint operation of the rotor and propeller controls is effected by a " conversion " lever 87, Fig. 6, with crank arms 88, 89. The arm 88 is connected to a link 74 coupled to the propeller clutch-operating link 66, Fig. 5. The arm 89 is connected to a link 127 which operates links 132, 146, 139, 140 connecting the ends of the levers 125, 130, 143, 147. A rod 75 attached to the lever 147 is coupled to the propeller pitch control rod 72, Fig. 5. The rotor clutch control rod 56, Fig. 5, may be connected to the rod 74 operated by the conversion lever 87, or may be operated independently by the pilot. Movement of the lever 87 thus operates the rotor and propeller clutches through rods 74, 56, 66, and the propeller pitch changing mechanism, to unfeather the propellers, through rods 75, 72, and at the same time alters the datum setting of controls (a), (b) and (c). The setting of control (a) is varied by members 89, 127, 125, 124, 117, 123 to incline the spider 112 in the nose-up sense and thereby trim the aircraft by the stern. Also, the pillar 135 and T-beam 133 are raised by movement of the members 132, 146, 143, 142, 141 to apply equal degrees of cyclic pitch control in the sense for increasing the disc-incidence of each rotor, and thus vary the setting of control (b). The movement of members 139, 137, 136 also causes nose-up rocking of the T-bar 133 to apply cyclic pitch control differentially to the forward and rear rotors, and thereby incline their lift vectors to increase their positive fore and aft dihedral angle. Control (c) is varied to reduce the collective pitches of all the rotors equally by lowering the pillar 114 and spider 112, by movement of the members 132, 130, 129, 128. Specification 599,990 is referred to.